The invention relates to transmissions in general, and more particularly to transmissions which employ pulleys or sheaves. Still more particularly, the invention relates to improvements in pulleys of the type wherein two coaxial flanges have confronting surfaces engageable with a portion of an endless flexible element (such as a belt or a chain) which transmits torque to or receives torque from the pulley. Pulleys of the type to which the present invention pertains can be utilized with particular advantage in transmissions of the type known as CVT (continuously variable transmissions), e.g., in the power trains of motor vehicles to directly or indirectly transmit torque between a prime mover (such as an internal combustion engine) and the wheels of the motor vehicle. Reference may be had, for example, to commonly owned U.S. Pat. No. 5,667,448 (granted Sep. 16, 1997 to Oswald FRIEDMANN for xe2x80x9cPOWER TRAINxe2x80x9d), to commonly owned U.S. Pat. No. 5,711,730 (granted Jan. 27, 1998 to Oswald FRIEDMANN and Armin VEIL for xe2x80x9cTORQUE MONITORING APPARATUSxe2x80x9d) and/or to published German patent application Serial No. 197 48 675 A1.
The just mentioned published German patent application Serial No. 197 48 675 A1 discloses two adjustable pulleys each having an axially fixed flange and an axially movable flange. The flanges have main sections provided with confronting conical surfaces, and conical liners which are bonded or otherwise affixed to the conical surfaces and are made of a wear-resistant material.
Published German patent application Serial No. 691 00 344 T2 discloses pulleys wherein the annular main sections of the flanges carry liners made of steel and being secured to the conical surfaces of the respective main sections by layers of adhesive made of polyurethane which is intended to absorb noise as well as to contribute to lower cost of the pulleys.
The disclosure of the commonly owned German priority patent application Serial No. 199 22 575.3 (filed May 17, 1999) and the disclosures of all U.S. and/or foreign patents and patent applications identified in the specification of the present application are incorporated herein by reference.
The aforementioned composite flanges exhibit the drawback that the direct connections between the liners and the annular main sections of the respective flanges are unreliable and can stand only relatively short periods of actual use. Furthermore, the material of the presently known and employed liners is also incapable of standing extensive periods of use, particularly in the aforementioned CVT transmissions. Thus, there exists an urgent need for high-quality pulleys or sheaves wherein the liners of composite flanges as well as the connections between such liners and the main sections of the respective flanges are superior to those employed in presently known pulleys.
An object of the instant invention is to provide a pulley wherein the liners are connected to the annular main sections of the flanges in a novel and improved way.
Another object of the invention is to provide novel and improved liners for use in the flanges of the above outlined pulleys.
A further object of the invention is to provide novel and improved means for centering the liners on the main sections of the respective flanges in a pulley, particularly in a pulley which is to be utilized in a continously variable transmission.
An additional object of the invention is to provide novel and improved connectors which can secure the liners to the main sections of the respective flanges and remain operative during the entire useful life of the flanges.
Still another object of the invention is to provide connectors which exhibit superior sound-absorbing or sound-deadening characteristics.
A further object of the invention is to provide a transmission which employs pulleys exhibiting the above enumerated desirable characteristics.
Another object of the invention is to provide a novel and improved method of making pulleys exhibiting the above-outlined desirable characteristics.
An additional object of the invention is to provide a novel and improved method of assembling the constituents of the above outlined pulleys.
Still another object of the invention is to provide pulleys having a useful life greatly exceeding those of the aforediscussed and other conventional pulleys.
A further object of the invention is to provide pulleys which can be mass-produced at a reasonable cost, which exhibit highly satisfactory acoustic characteristics (sound absorbency), and the useful life of which is surprisingly long even if such pulleys are utilized under circumstances wherein they are exposed to temperatures which fluctuate within a wide range and to highly pronouced mechanical (such as frictional, torsional and other) stresses.
One feature of the present invention resides in the provision of a pulley comprising a composite rotary flange including an annular section rotatable about a predetermined axis and having an annular surface (normally a conical surface) extending at least substantially radially of the predetermined axis, a wear-resistant liner adjacent the annular surface, an insert (particularly a substantially disc-shaped insert) between the liner and the annular surface, and means for connecting the insert to the annular section and to the liner. The connecting means comprises a first unit having means for affixing or securing the insert to the annular section and a second unit having means for affixing or securing the insert to the liner. The securing means of the first unit is offset relative to the securing means of the second unit as seen in at least one of a plurality of directions including axially and radially of the flange.
A first side of the liner confronts the insert, and a second side or surface of the liner is arranged to be engaged by an endless flexible element (e.g., a belt, a band or a chain) of a continuously variable transmission, e.g., a transmission in the power train of a motor vehicle.
In accordance with one presently preferred embodiment of the invention, the insert includes a disc-shaped annular metallic member, and the securing means of at least one of the connecting units includes rivets which secure the metallic member to the annular section or to the liner. To this end, the disc-shaped insert can be provided (e.g., in an upsetting or an equivalent machine) with holes bounded by collars extending in substantial parallelism with the predetermined axis, and the collars can form part of at least one of the connecting units. The collars can include (a) a first set of collars extending away from the liner and forming part of the first connecting unit, and (b) a second set of collars extending away from the annular section and forming part of the second connecting unit. If the securing means of the two units include rivets, the annular surface can be provided with first recesses for the rivets of the first unit, and that side of the liner which confronts the insert can be provided with recesses for the rivets of the second unit. The rivets can include deformed malleable bodies of a suitable metallic material, and such rivets are received in the collars and are anchored in the respective recesses. The malleable bodies are or can be deformed as a result of the application of axial forces to the liner and/or upon the annular section in the direction(s) toward the insert. The rivets are preferably configurated in such a way that each collar fills a first portion and each of the deformed bodies fills the remaining portion of the respective recess.
The first unit of the connecting means can be located at or nearer to the radially outer portion of the annular surface, and the second unit of the connecting means can be located at or nearer to the radially inner portion of the annular surface, or vice versa. The securing means of at least one unit can include rivets, and the insert can be provided with slots (e.g., with arcuate slots extending circumferentially of the annular section) which are disposed between the inner and outer portions of the annular surface.
In accordance with another presently preferred embodiment, the insert includes or constitutes a disc-shaped annular member having a central portion and a peripheral portion located radially outwardly of the central portion. The peripheral portion is provided with pluralities of alternating first and second flexible tongues respectively extending clockwise and counterclockwise (as seen circumferentially of the annular surface), the securing means of the first unit includes means for affixing the first tongues to the annular section, and the securing means of the second unit includes means for affixing the second tongues to the liner. At least one of the first and second units of the connecting means can comprise rivets, and the tongues can be configurated and made in such a way that each thereof has a first end portion which is of one piece with the central portion of the insert and a free second end portion which is spaced apart from the respective first portion (as seen circumferentially of the annular surface). The rivets of the first unit serve to affix the second end portion of each first tongue to the annular section, and the rivets of the second unit serve to affix the second end portions of the second tongues to the liner.
When properly installed, the insert can be stressed to pull the liner axially of and toward the annular section.
The securing means of at least one unit of the connecting means can include means for bonding the insert to the annular section or to the liner. The just mentioned insert can constitute a laminate including two outer layers and a central layer which is sandwiched between the outer layers. At least one layer of the laminate (e.g., the two outer layers) can contain or consist of a sound absorbent material. One of the outer layers can be bonded to the liner and to the central layer, and the other outer layer can be bonded to the annular surface of the annular section and to the central layer. The latter can be provided with slits which divide it into first and second panels or fields respectively bonded to the one and the other outer layer. The central layer of the laminate can constitute an annular disc, and the fields of such disc can be configurated and distributed in such a way that the layers can move relative to each other radially of the predetermined axis and in the axial direction but not in the circumferential direction of the annular surface of the annular section of the flange.
It is also possible to employ a central layer which comprises several first and second at least substantially concentric rings which alternate as seen radially of the predetermined axis; the first rings can be bonded to one of the outer layers of the laminate and the second rings are bonded to the other outer layer of such laminate. At least some of the rings can be made of or can contain a fibrous material.
The insert can comprise or constitute a washer having a first side partially bonded to the annular surface of the annular section and a second side partially bonded to the liner.
The flange can further comprise means for non-rotatably centering the liner and/or the insert on the annular section of the flange. The centering means can comprise external teeth on the annular section and internal teeth mating with the external teeth and provided on the liner or on the insert. Alternatively, the centering means can comprise an external shoulder at the surface of the annular section and a complementary internal surface provided in the liner and/or in the insert and non-rotatably surrounding the shoulder. Still further, the centering means can comprise a peripheral surface provided on the annular section and an annular extension provided on the liner and/or on the insert and snugly surrounding the peripheral surface. The peripheral surface can be provided with external teeth, and the extension(s) can be provided with internal teth in mesh with the external teeth.
At least one side of the insert can be provided with a coat which exhibits one or more desirable characteristics such as pronounced resistance to wear, pronounced hardness, acting as a solid or liquid lubricant and enhancement of smoothness of such side of the insert.
At least one side of the insert can be provided with one or more lubricant-receiving and distributing channels.
Highly satisfactory results were obtained with inserts made, at least in part, of high-quality sheet steel or bronze.
The annular section of the flange but particularly the liner can consist of a metallic material which has undergone at least one of the treatments including case hardening, tempering and induction hardening. Highly satisfactory results were obtained with a flange employing a liner consisting of a case hardened metallic material.
Another feature of the present invention resides in the provision of a method of making a pulley of the type having flanges at least one of which includes (a) an annular section rotatable about a predetermined axis and having a preferably conical annular surface, and (b) a liner which is adjacent the annular surface and is engageable by an endless flexible element (such as a band, belt or chain) for transmission of torque to and from the pulley. The method comprises the steps of placing an annular disc-shaped (composite or one-piece) insert between the annular surface of the annular section and the liner, connecting first portions of the insert to the annular section, and connecting different second portions of the insert to the liner.
The method can further comprise the step of centering the liner and/or the insert on the annular section.
At least one of the connecting steps can include bonding the liner or the annular section to the respective portions of the insert. Alternatively, or in addition to bonding, at least one of the connecting steps can include riveting the liner or the annular section to the respective portions of the insert. For example, the connecting steps can include providing the insert with first and second sets of flexible tongues, affixing (e.g., riveting) the tongues of one of the sets to the annular section, and affixing (e.g., riveting) the tongues of the other set to the liner.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved pulley itself, however, both as to its construction and the modes of assembling and utilizing the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.